Nanotechnology is not some abstract sci-fi future fantasy. Nanotechnology
is simply engineering on a scale slightly smaller than usual, and it can
provide simple and useful solutions to very real problems that concern
all inhabitants of this planet. One of the areas where nanotech can realize
some breakthrough technical applications in the near future is the production
of clean water, a scarce commodity already, water shortage is set to produce
pressing problems in the near future. On this conference it became obvious
however that solutions are at hand; effective, cheap, and available as
On Monday September 30, 2004, The Club of Amsterdam and Cientifica together
hosted the first international conference on nanotechnology and water
“NanoWater”, at the RAI Congress Center in Amsterdam. Nanotechnology and
water, an unlikely combination? Not really. In fact most of the technology
presented at the conference can be defined as a solution to the following
assignment: construct a really fine-grained way to sieve water.
Water is the essence of life. Most water on this planet (>95%) is seawater.
Most of the drinkable fresh water is frozen on the North and South Poles,
and much of the remaining available fresh water is polluted or simply
in the wrong place. 75% of global precipitation occurs in areas containing
less then a third of the world population.
With over 20% of the world's population having no access to safe drinking
water, there is a shortage of clean fresh water now, and as developing
countries raise their standard of living, this shortage will increase.
Global water consumption, doubling every 20 years, is increasing much
faster than the population. So if you find a smart (and cheap) way to
sieve out anything from micro-organisms like bacteria and viruses to salt
ions, you solve a lot of problems for a great many people, and you can
make a lot of money in the process. Research into nanotechnology is receiving
significant government subsidies in the US and Europe, and the total global
market for clean, drinkable water is an estimated 400 billion dollars
This is the theme of the day: nano filtration to clean up water. There
are several competing methods for filtering water. Clean water is expensive
in the third world, where, in real terms, people actually pay more money
for clean water than citizens of developed countries like the USA. One
of the bleak ironies of our modern world is that an essential product,
virtually free to us rich citizens, is very expensive for the poor of
the world. They pay up to 25% of their real income to have access to clean
The first speaker is Kevin McGovern of McGovern Capital LLC. Mr.
McGovern explains how his investment firm is trying to spearhead the nano
revolution. One of his ventures, KX Industries, is producing nano-scale
filters that will filter out items as small as bacteria and viruses, for
the specific purpose of eradicating waterborne disease, one of the main
killers in developing countries. The product is cheap, and effective;
KX Industries has actually received an FDA approval for its filters as
an antiseptic. It seems that the poorest, most destitute regions of our
world will benefit from nanotech's impact first. Are local conditions
in developing countries changing their role from daunting problems to
innovation drivers? “In some cases, Yes”, replies McGovern, who sees a
huge market for KX Industries' products in developing countries. The nano
filters by companies like KX Industries are very likely to change that,
by providing abundant, cheap water.
One method is purely mechanical, meaning that a filter with cavities (“pores”)
smaller than the undesirable particles can extract those. Aquamarijn
Research BV, a Dutch firm, uses semiconductor production technology,
where patterns are etched into thin wavers of silicon, to make filters.
The pores of these filters are small enough to sieve out most particles
and bacteria, but too large to extract viruses and synthetic pollutants
like pesticides, but the development look promising.
Another way to filter water is by reversing the naturally occurring process
called ‘osmosis'. Osmosis occurs when a concentrated solution, a fluid
like water with a large amount of other atoms or molecules floating around
in it, is separated from a less concentrated solution (less atoms and
molecules) by a semi-permeable membrane. Nature has a tendency towards
equilibrium, so water is drawn through the membrane towards the side with
the higher concentration. This reduces the difference in concentration
between the two sides of the membrane. Reverse osmosis is the process
whereby pressure is applied to a concentrated solution (dirty water),
forcing the fluid through a very fine membrane, resulting in a (virtually)
pure fluid. The pores in these membranes are so small that reverse osmosis
can be used for desalination, i.e. turning seawater into drinking water,
by taking out the salt.
Reverse osmosis is slow and expensive, since applying the pressure requires
large amounts of energy. Professor Raphael Semiat, Grand Water Research
Institute of the Israel Institute of Technology, explains that significant
cost reductions are being achieved in his research department. The latest
desalination plant (in Ashkelon, Israel) produces drinking water from
the Mediterranean basin at a cost of 50 dollar cents per cubic meter (1000
It is also possible to use osmosis as a process of filtering polluted
water. The US military has a plastic bag containing a sucrose solution
separated from the outside world with a membrane. When this bag is submerged
into any quality of water after 18 hours the concentrated solution in
the bag will draw about 2 liters of clean water through the membrane.
Since osmosis is only effective when you start from a concentrated solution,
the end product is lemonade, not water, which is not always what you want.
However, for military purposes (or camping and trekking) this is ideal
since the process can provide a nutritional broth. The challenge to use
osmosis to provide pure water is being met by the British research organization
NanoMagnetics, which produces small magnetic particles encapsulated
by natural enzymes that set the same osmotic process in motion, but in
the end all particles can be taken out from the fluid by applying a simple
magnetic field. Elegant and effective, NanoMagnetics now faces the task
of up-scaling the production of these Nanomagnets.
The effectiveness of filters is by and large a function of the size of
the pores. Smaller holes mean better filtration. But that is not the only
possible solution. Many particles, organic and synthetic, are sensitive
to an electrical charge. Fred Tepper of the US company Argonide
explains how his company has created a filter comprising oxidized aluminum
nanofibers, on a glass fiber substrate. These alumina fibers are positively
charged, which enables them to filter bio-organisms such as bacteria and
viruses from the water flow. Even though the pores in this filter are
relatively large, the end result is extremely effective, because the process
provides a much higher flow rate than traditional membranes. The filter
retains up to 99.999% of viruses, is in production as we speak, and can
be used to clean water by applying muscle force. No extra energy needed,
ideal for rural contexts.
Filters based on nano-technology are a very practical application, providing
a low-cost – less than $0,25 per liter – solution. As more people in the
third world die for lack of clean water than from any other cause, nano-technology
can be said to provide genuine benefit to mankind. Not just in the third
world, but also in the developed world many situations exist where this
type of technology can make a substantial difference.
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